I'm predicting it will be a big name, but someone i don't think will be a great fit for the book.
Marvel is not going to want a big break from what's been going on....but i might be wrong on that because assembled is clearly very traditional.
Say whatever you will about Bendis..this is probably the high point in all of Avengers history..and Bendis was the writer of the book when that happened (not to mention he gave creative council on the film) ..it's over 1 billion now, and yes Marvel comics will benefit.
I do take issue with the fact that Ultimates "isnt the Avengers"...that movie was more like Ultimates than it was Stern or Busiek.
But there was also a nice whimsical vibe of bygone 616 tales and characters there that really sold it to me as one of the best comic flicks ever...it didnt take itself too seriously.
While some people think the movie sales and comic sales never correlate, I'd be surprised if the book doesnt get a nice boost.
So expecting more Hand Ninjas, dark story lines, and street level, stories is possible
I'd guess it will be a marvel "golden boy" like Millar, JMS , Hickman, Fraction, or Loeb. (I do like Hickman , some fraction, and Millar's Ultimates)...
That's my short list..with Loeb being the front runner...marvel doesnt get it with him, and his stuff sells.
Waid and Remender would be some dark horse canidates I'd much prefer..
Slott would be my top choice and is a possibility...but I think marvel sees his mighty run as somewhat of a failure and he's got his hands full with spidey.
But I have a new found respect for Bendis...he took the Avengers at it's lowest point in fan support and leaves it with it's best...sales wise he performed well and brought the book to it's pinnacle of flagship status...and left as such..good for all avengers fans.
I've never liked much of it, but I am digging his Assembled, and have liked some of it.
Now some one please clean up this wonder man business!